Relay



0. s. FIELD Sept. 22, 1931.

RELAY Filed April 26; 1929 tlon Insu latlon ATTORNEY F|e.4. 7 F155.

Patented Sept. 22, 1931 UNITED STATES PATENT OFFICE OSCAR S. FIELD, OF ROCHESTER, NEW YORK, ASSIGNOB TO GENERAL RAILWAY SIGNAL COMPANY, OF ROCHESTER, NEW YORK nanny Application filed April 26,

to give it either a slow pick-up time relative to its release time or vice versa.

In practice it is often desirable to have a relay either slow to release relative to its pick-up time, or slow to pick up relative to its release time.

For example, in the case of cut sections in which a signal block is divided into sections and provided with a track relay and source of energy in each section, it sometimes occurs that on a train leaving the first section and entering the second section, the track relay connected across the first section picks up before the track relay connected across the second section releases, whereby to momentarily leave the two track relays up, even though the block be occupied. With a signal at the entrance end of the block energlzed through front points in seriesof these two track relays, it is obvious that a flashing of the signal occurs on a train passing out of the first section and into-the second section. To avoid this, all that is necessary is to make the track relays slow enough to pick-up relative to their drop-away times, and this can be readily accomplished in accordance with the present invention.

Such slow pick-up characteristics are also desirable in signalling systems of the absolute-permissive-block type.

In numerous cases it is desirable to make a relay slow to release relative to its pick-up time, as for example, to care for cross-overs, dead sections and the like in connection with automatic train control devices, as is well recognized by those skilled in this particular art.

It is proposed, in accordance with this invention, to provide the usual cores of a tractive type relay such as shown in application Ser. No. 126,914 filed July 27, 1926, in the name of O. S. Field, with copper washers, and with a magnetic bridge interconnecting 1 the lower ends of the cores so as to magneti cally shunt the armature. In this manner, by variously adjusting the number of copper 1929. Serial No. 358,198.

washers, and the number of lamina of which the magnetic bridge is composed, a rela having a normal fixed ratio of pick-up time to drop-away time, can be adjusted to vary this ratio in either direction, so as to make the relay relatively quick to pick-up, or relatively quick to release.

Further objects, purposes and characteristic features will appear as the invention progresses, reference being had to the accom- I panying drawings, showing, solely by way of illustration, and not in any mannerin a limiting sense, two forms which the invention can assume. In the drawings Fig. 1 is a side elevational view, with parts shown in section, of portions of a relay exemplifying one form of the present invention.

Fig 2 is a front elevational view, with parts shown in section, of a portion of the relay of Fig. 1, but shown in a more diagrammatic manner. Y

Fig. 3 is a front elevational view, with parts shown in'section, of a' slightly modified form of the invention.

Fig. 4 is a perspective view of one of the choke elements employed in the invention.

Fig. 5 is a perspective view of one of the lamina members employed in the invention.

Referring now to the drawings, and first to Fig. 1, there is here shown a relay casing C,

having a top plate TP connectedto the casing C by a bolt 1, or the like. The top plate TP carries fixed front contacts 2, and fixed back contacts 3, for cooperating, respective ly, with movable front contacts 4 and back contacts 5, carried by an articulated contact finger 6, connected to an armature 7 pivoted at 8 to coact with pole shoes 9, of core members 10. The core members 10 are, interconnected at their upper ends by a back strip 11, and carry coilsor windings 12, in the usual manner, which, when energized, cause flux to flow through the cores and back strip in series, lead-in wires 13, connected to terminal posts 14, being provided for energizing the coils 12.

The structure above described, is more particularly described in application Ser. No. 126,914, above referred'to, to which reference ishereby made for a more complete descripthe drop-away time for the relay is increased tion of the structure involved.

Coming now more particularly to the present invention, the windings 12 are made short enough to leave, the lowerends of the cores 10 free, for receiving copper washers or their equivalents 15, and bridging lamina 16 of transformer iron for bridging the lower ends of the cores 10.

One of the copper washers 15, employed in this invention, is shown in detail in Fig. 4.

Likewise one of the lamina 16, employed in this invention, is shown in detail in Fig. 5.

In the form of invention shown in Fig. 3,

the copper washers 15 are omitted, the cores 10 carrying merely the windings 12, and in addition thereto, the magnetic bridge formed by the lamina 16.

The sizes and proportions of the various parts can of course be varied in accordance with the attendant conditions. It has been found, in practice, that goodresults have been obtained by using copper washers 21%; in diameter, and in thickness.

In connection with the ma etic bridge, it has been found, in practice, t at good results have been obtained b having the lamina 16, comprising this bri ge, .015" in thickness and made of 00d grade transformer iron. These laminations, as shown in Fig. 5, each comprise a strip of iron, punched or otherwise formed, with two holes, preferably punched, so as to permit ready threading of the lamina onto the cores 10.

It is apparent from the above description that the number of copper washers 15, and the number of lamina 16, can be readily adjusted at will.

The effect of the copper washers 15, used in the relay, is to choke back energizing current in windings 12, whereby, with a given applied voltage, current will build up slower when the copper washers are present than when they are omitted, necessarily to somewhat retard or lengthen the pick-up time for the relay. On shunting, the relay however,- as occurs in railway practice by the shunting effect of the wheels and axles of an occupying car, the decay of fluxdin the cores 10 and armature 7-is greatly impeded, due to the choking efl'ect of these co'pper washers, so that to a much greater degree than is the pick-up time. In this manner, the employment of the copper washers makes for a relay having a slow'drop-away relative to its pick-up, and

' the greater the number of copper washers employed, the slower will be t e relative dropawa time.

' e reason for the choke washers 15 operating to increase the time for drop-away by a; much greater amount than the time for pick up, may be accounted for, by the factthat during pick-up, energy is being applied to the relay, whereas during drop-away, no energy was is being applied, but the relay is merely shunted as by an occupying car.

The operation and the effect of the magnetic bridge constituted by the lamina 16, is such as to increase the time for pick-up by a much greater amount than it increases the time for drop-away, and this relative efiect is increased, according as a greater number of lamina is employed.

This may be explained by the fact that, before the armature 7 is picked up, that is, with the armature 7 in dropped-away position, the magnetic bridge formed by lamina 16 is very effective in shunting out themagnetic path between the lower ends of the cores 10 and including the armature 7, since the armature path is very poormagnetic path due to the large air gaps between the armature and the pole faces, hence the magnetic bridge is very eflective in its shunting action.

After the armature 7, however, has picked up, the effect of the magnetic bridge in shunting the armature is not so efiective as formerly, because, 1n plcked-up condition, there are two magnetic paths of substantially equal reluctance, one including the magnetic bridge, and the other including the armature 7. Hence, under picked-up condition, while the magnetic brid e constitutes a shunt around the armature but one of relatively minor importance, and thus it does not increase the drop-away time in anywhere nearly the same proportion that it increasesthe pick-up time.

This can be appreciated by considering that, upon energization of the windings '12, current builds up in such windings to build up flux in the cores, the magnetic bridge constituted by lamina 16 and the armature 7. The armature 7, however, being in a magnetic circuit of high reluctance is traversed by very little flux,the major portion of the flux passing through the magnetic brid e. It isthus necessary to first increase the ux density in the magnetic bridge substantially to the saturation point,- before flux in any considerable amount will traverse the armature 7 so as to bring the flux in the armature up to the point required for pick-up of the relay. This consideration shows how the magnetic bridge Y very materially increases the time required for pick-up of the relay, as compared with a like relay with the magnetic bridge omitted.

Another way of explaining the fact that the magnetic bridge or shunt operates to increase the pick-up time by a much greater percentage than it does the drop-away time, is that, with the magnetic shunt, the flux produced by the 12 is practically all taken by the magnetic bridge until the bridge is saturated or substantially saturated. Hence a much higher fluxdensity in the cores 10 must be produced .before the flux through the air gap and in the armature 7 reaches the pick-up value, than is the case with a like re-' lay but without the magnetic shunt. In other 7 words, the picking up of the armature 7 occurs only at a much higher flux density of the relay cores 10, when the shunt is employed, than when the shunt is not employed. Accordingly, on cutting off energy from the relay, as by a track shunt, the decrease in core flux necessary to produce drop-away conditions in the armature is attained much more rapidly, than if the cores were worked at a lower flux density for pick-up conditions in the armature. That is, the rate of decay of flux is more rapid at high flux density than at lower flux density.

For the above several reasons, as now understood, the magnetic bridge formed by the lamina 16 operates to increase the pick-up time of a relay to a much greater amount than it does to increase the drop-away time, and

hence it makes for a relatively slow pick-up and quick drop-away relay.

To sum up the above, the copper washers 15 operate to produce a relay having a longer release time than a pick-up time, that is, to produce aslow release relay; while the magnetic bridge operates to produce a relay having a longer pick-up time than a release time, so as to result in a slow pick-up relay.

It is obvious that any given relay can be furnished with various amounts of copper washers and of lamina in the manner contemplated by this invention, and, depending on the relative proportions of the two, the resulting relay will have outstanding quick pick-up or quick release characteristics.

A specific example may tend to clarify the above description. The type K relay, as normally constructed in accordance with application Ser. No. 126,914, referred to above, has a pick-up time of .15 seconds and a dropaway time of .05 seconds, so that the pick-up requires three times as much time as does the drop-away. WVith no copper washers such as 15, employed, but with a magnetic bridge formed by 10 lamina of transformer iron with each lamination .015 in thickness, the pickup time was .75 second and the dropaway time .1 second. From this it is seen that the magnetic bridge increased the pickup time to five times its former value, while it increased the drop-away time to only double its former value. That is, the magnetic bridge increases the ratio of pick-up time to drop-away time from the normal ratio of the type K relay of i 'g=3,toaratio of: %=7.5. I

By employing copper washers'only, the drop-away time can be increased to a greater amount than is'the pick-up time, so that, with the type K relay, for example, the normal ratio between pick-up and drop-away times, of 3, can be changed by the use of these copper washers to 2 or 1 or whatever is desired.

By employing both the choke washers 15, and the magnetic bridge formed by lamina 16, as shown in Fig. 2, the opposing effects of the two on pick-up and drop-away times, can be variously balanced or unbalanced to give, within reason, any desired characteristic with regard to pick-up and'release times.

The various shapes and sizes of elements employed in the. invention, as described above, are given only by way of example, and can be varied as conditions and for practice dictates, to accomplish the desired ends,'without departing from the present invention.

Furthermore, the above rather specific description of one'form of device embodying the present invention has been given solely by way of illustration, and is not intended, in any manner whatsoever, in a limiting sense. Obviously, this invention can assume many different physical forms, and is susceptible of numerous modifications, and all such forms and modifications are intended to be included by this invention, as come within the scope of the appended claims.

Having described my invention, I now claim v 1. In a relay relatively slow to pick up, or

to release, means magnetically shunting the relay armature to a greater or lesser extent, and means choking the I magnetic path through the relay cores to a greater or lesser extent, depending on the original characteristics of the relay and the extent of the said magnetic bridging, whereby to make the relay relatively slow to pick up, or relatively slow to release, depending, respectively, upon the preponderating efiect of the bridging or the choking.

2. In a relay, in combination with a U; shaped core, a coil on the core, and an armature cooperating withthe core ends a mag netic bridge across the ends of the cores, to magnetically shunt the armature, and choke members on the core, readily variable in a coil on the core, and an armature eooperating with the core, a fixed, continuous, laminated magnetic bridge positioned to magnetically shunt the armature, the lamina composing the bridge being constructed to be readily variable in number, at will, to permit adjusting the slow pick-up effect produced by the bridge, and choke means on the core, readily variable in amount, to offset, to varying extents, the effect of the bridge, whereby to vary relative pick-up and drop-away values at will.

4. In a relay, in combination, spaced magnetic cores inter-connected at one end by a back strap, an armature movable to interconnect the other ends of the cores, an energizing winding for the cores, a magnetic bridge, in multiple with the armature, across the lower ends of the cores and choke means, readily variable in amount, on the cores.

5. In a relay,.in combination, spaced mag- 5 netic cores inter-connected at one end by aback strap, an armature movable to inter-connect the other ends of the cores, an energizing winding for the cores, and a fixed magnetic bridge shunting the armature and com- I m posed of stamped out lamina, each of which is punched to be readily threaded onto the two cores.

6. In a relay, in combination, spaced magnetic cores inter-connected at one end by a 15 back strap, an armaturemovable to interconnect the other ends ofthe cores, an energizing winding for the cores, 2. fixed magnetic bridge shunting the armature, and choke means on the cores.

20 7. In a relay, in combination, spaced magnetic cores inter-connected at one end by a back strap,- an armature movable to interconnect the other ends of the cores, an energizing winding for the cores, a fixed magnetic bridge, in multiple with the armature, across the lower ends of the cores, and choke washers threaded onto the cores.

8. In a relay, in combination, spaced magneticcores inter-connected at one end by a back strap, an armature movable to interconnect the other ends of the cores, an energizing winding for the cores, a fixed magnetic bridge shunting the armature and comosed of lamina, each of which is formed to e threaded onto the two cores, and choke washers of hon-magnetic material, threaded onto each oi the cores.

9. In a relay, in combination with a core having two spaced ends, a coil on the core, and an armaturecooperating with the ends of the core; a fixed continuous laminated magnetic bridge constituted by a plurality of. flat stam'pings, each perforated to receive the core ends, threaded onto the ends of the core to magnetically shunt the armature.

, 10. In' a relay, in combination with a core having two spaced ends, a coil on the core, and an armature cooperating with the core ends; a fixed continuous laminated magnetic bridge across the ends 'of the core to magnetically shunt the. armature, the lamina composing the bridge being flat stampings threaded onto the core ends, whereby to be readily variable in number, at will, to permit adjusting the slow acting effect produced by the bridge.

In testimony whereof I afiix my signature.

OSCAR S. FIELD. 

